Wall-E Prototype I TCSP #8 Safety and Reliability Analysis Team 1 Xin Jin Ranmin Chen Hang Xie Zelun Tie

Project Overview The design project Wall-E Prototype I is an intelligent automated trash collecting robot with obstacle detection capability. The robot responses to either user’s direct manual control, or the object tracking software, to locate and collect the targeted trash object.

Reliability Calculations: Component Selection Microcontroller: PIC24FJ256GA106 Switch-Mode Regulator: LM2596 Xbee Pro Fuel Gauge: BQ2010

PIC24FJ256GA106 Parameter NameDescriptionValueComments C1C1 Die Complexity.2816-bit microprocessor πTπT Temperature Factor.77T C = 50 θ JC = 22 P =.5 T J = T C + θ JC *P = 61 C2C2 Package Failure Rate.032Nonhermetic SMT (64 pins) πEπE Environmental Factor 4.0Ground Mobile πQπQ Quality Factors10Commercial or Unkown Screening Level πLπL Learning Factor1.02+ Years in Production Overallλ p = 3.436MTTF ≈33.5 years Monolithic Bipolar and MOS digital Microprocessor Devices λ p = (C 1 * π T + C 2 * π E ) * π Q * π L

Switch Mode Regulator(LM2596) Parameter NameDescriptionValueComments C1C1 Die Complexity – gates πTπT Temperature Factor 20T C = 50 θ JC = 20 P = 3 T J = T C + θ JC *P = 110 C2C2 Package Failure Rate.019Nonhermetic SMT (5 pins) πEπE Environmental Factor 4.0Ground Mobile πQπQ Quality Factors10Commercial or Unkown Screening Level πLπL Learning Factor1.02+ Years in Production Overallλ p = 4.76MTTF ≈24 years Monolithic MOS Digital and Linear Gate/Logic Array Devices λ p = (C 1 * π T + C 2 * π E ) * π Q * π L

Xbee Pro Parameter NameDescriptionValueComments C1C1 Die Complexity to gates πTπT Temperature Factor.58T C = 50 θ JC = 20 P = 0.7 T J = T C + θ JC *P = 64 C2C2 Package Failure Rate.01Nonhermetic DIP (20 pins) πEπE Environmental Factor 4.0Ground Mobile πQπQ Quality Factors10Commercial or Unkown Screening Level πLπL Learning Factor1.02+ Years in Production Overallλ p = 3.648MTTF ≈ years Monolithic MOS Digital and Linear Gate/Logic Array Devices λ p = (C 1 * π T + C 2 * π E ) * π Q * π L

Fuel Gauge (BQ2010) Parameter NameDescriptionValueComments C1C1 Die Complexity to gates πTπT Temperature Factor.51T C = 50 θ JC = 10 P = 0.5 T J = T C + θ JC *P = 60 C2C2 Package Failure Rate.0072Nonhermetic SMT (16 pins) πEπE Environmental Factor 4.0Ground Mobile πQπQ Quality Factors10Commercial or Unkown Screening Level πLπL Learning Factor1.02+ Years in Production Overallλ p = 1.716MTTF ≈ 66.5 years Digital IC: Monolithic MOS Digital and Linear Gate/Logic Array Devices λ p = (C 1 * π T + C 2 * π E ) * π Q * π L

Failure Mode, Effect Criticality Analysis: Functional Blocks Microcontroller Block (A) Wireless Communication Block (B) Power Supply Block (C) Motor/Servo Control Block (D)

FMECA: Microcontroller Block Failure No. Failure Mode Possible CausesFailure EffectsDetection Method Criticality A1PIC24 not able to read characters through UART Can be caused by failure of any component within the micro circuit, Different data format, Failure of Xbee, Software error Loss of ability to wirelessly control the robot Inspection of Rx pin via probe low A2Failure of PWM peripheral Failure of PIC24, Failure of H- bridge, Bad connection Software error The robot out of control Inspection of the PWM pins via oscilloscope High A3Ultrasonic signal not received at PIC24 ATD pin Failure of Ultrasonic sensor, Failure of PIC24, Software error Failure to avoid obstacles Inspection of the ATD pins via probe Observation low

Failure No. Failure Mode Possible CausesFailure Effects Detection Method Criticali ty A4Failure to Reset Reset Pushbutton Failure, Microcontroller Failure Loss of ability to reset microcontroll er Observationlow FMECA: Microcontroller Block Wireless Communication Block B1Xbee not able to communica te with the Atom board Incorrect baud rate, Failure of Xbee Incorrect COM port settings in on the Atom board Loss of ability to wirelessly control the robot Inspection of Xbee Tx, Rx pins via probe low B2Failure of transmittin g data between Xbees Out of range, Unmatched Xbees Loss of ability to wirelessly control the robot Inspection of Xbee Tx and Rx pins via probe low

FMECA: Power Supply Block Failur e No. Failure Mode Possible CausesFailure EffectsDetection Method Criticalit y C13.3V rail = 0VBad connection, Battery failure, Failure of LM2596 Failure of inductor, input/output capacitors in the power supply circuit No power for all the components on the PCB Inspection of the 3.3V power rail via probe low C23.3V rail > 3.3V Shorted circuit, Failure of LM2596 Failure of inductor, input/output capacitors in the power supply circuit Risk of overheating, Burning the micro, fuel gauge and Xbee Inspection of the 3.3V power rail via probe, smell High

FMECA: Motor/Servo Control Block Failu re No. Failure ModePossible CausesFailure EffectsDetection Method Criticalit y D1Motor rotates to fast or too slow H-bridge overheated, Battery failure, Incorrect microcontroller PWM output signal, Motor failure The robot runs too fast or too slow Inspection of H-bridge input and output signal via probe low D2 Mechanical arm failure Incorrect PWM duty cycle, Servo failure, Bad connection Loss of ability to pick up the ping-pong ball Observatio n, inspection of servo input signal low

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